One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,3,4)(5,6,10,11)(7,9,8,12)(14,17)(15,16)(22,26)(24,27)(6,11)(9,12)(13,14)(15,20)(16,19)(17,18) involution — undirected(5,7,10,8)(6,9,11,12)(13,15,18,16)(14,19,17,20)(21,22)(23,27)(24,28)(25,26)(1,2)(3,4)(5,8,10,7)(6,9,11,12)(13,16,18,15)(14,19,17,20)(21,23,25,28)(22,27,26,24)(5,9)(6,8)(7,11)(10,12)(13,17,18,14)(15,20,16,19)(21,24,25,27)(22,28,26,23)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.